1. Field of the Invention
The present invention relates to a portable communication tool, such as a mobile phone and a PHS (Personal Handyphone System), and more relates to structures of sound output holes for outputting sound from a speaker.
2. Background Art
Recently, portable communication tools are being miniaturized more and more, such as mobile phones and PHSs, while equipping various functions of, for example, a television set, a videophone, and the like. Under the circumstances, it becomes necessary to provided a speaker besides a receiver for equipping the functions. Sound from the speaker is output through a plurality of sound output holes formed in a cabinet provided at the front of the speaker. Japanese Patent Application Laid Open Publication Nos. 9-215076A and 2002-152871A disclose such portable communication tools, for example.
In Japanese Patent Application Laid Open Publication No. 9-215076A, a speaker is provided at the reverse face of a cabinet, and through holes and dummy holes are formed at the front of the speaker. Further, the dummy holes are set to have a diameter of 3 mm or smaller and a depth of 0.5 mm or larger or set to have a bottom in a conical shape, a trapezoidal shape, or a hemispherical shape to cause diffuse reflection rather than direct reflection of light entering in the dummy holes. This arrangement makes it difficult to distinguish between the through holes and the dummy holes in view of outward appearance with a result of improved appearance.
In Japanese Patent Application Laid Open Publication No. 2002-152871A, dummy holes include first recessed parts formed in the front face portion of a transparent resin panel and second recessed parts formed in the back face portion of the transparent resin panel so as to be opposite the first recessed parts, and at least a region where a cabinet is in contact with the second recessed parts is colored in the same color as a diaphragm of a speaker mounted at the cabinet. This removes unnaturalness of difference in outward appearance between the sound output holes for the speaker and the dummy holes to contemplate excellent design. Also, the strength as before is maintained with the transparent resin panel, which is easily molded. This means a cabinet with a transparent resin panel formed by dies at low maintenance cost.
Referring to sound output from one speaker through sound output holes formed in a cabinet, it is known that change in positions of the sound output holes leads to change in quality of the output sound.
It is essential, however, to place importance on product design, and therefore, the sound quality falls in conflict with product design.